Bug discovery could slash costs and cut carbon footprint of water treatment

The team, led by Ameet Pinto, is working on an EPSRC-funded project in collaboration with the University of Michigan. Analysing bacteria found in drinking water system in the US, they detected a previously-unknown strain that is capable of transforming ammonia into nitrates in a single step.

In existing water treatment systems, ammonia removal is a two-stage process involving two different strains of bacteria. First, the ammonia is converted to nitrites, and then in the second step these are oxidised to nitrates that can then be converted into nitrogen gas and evaporated safely from the water. One drawback of this is that the process requires large amounts of electricity. According to the EPSRC, two to three per cent of all electricity usage in Europe and the US is used for wastewater treatment, and some 30 per cent of this can be attributed to ammonia removal processes.

The newly discovered bacterial strain has been given the name commammox (complete ammonia oxidising) bacteria. Other research groups have now also detected it in wastewater plants, groundwater and aquaculture systems.

“This discovery took us completely by surprise,” Pinto said in a statement issued by the EPSRC to coincide with World Water Day. "The discovery of a single microorganism capable of full nitrification will have a significant impact on our understanding of the nitrogen cycle and on efforts to manage nitrogen pollution. The potential is there for the wastewater treatment sector to exploit this breakthrough, which other teams in Europe have made in parallel with us. That would be an important step towards informing the development of robust approaches in terms of cutting costs and reducing carbon emissions associated with generating the huge amounts of electricity that the sector uses.”

Pinto's project, lasting two years, is receiving around £250,000 from the EPSRC. It has two goals, one of which is to develop an "engineered assembly" of naturally-occurring microbes that can kill pathogens at the water treatment plant and continue to work as a protective barrier when the water is pumped into the supply system, thereby removing the need for chemical disinfection. Another aim is to identify microorganisms in drinking water that can be of potential benefit to human health.

The findings of the Healthy Drinking Water project are scheduled to be published later this year.